Method of producing magnetic head

ABSTRACT

The use of a Nd-YAG laser or excimer laser enables easy formation of protrusions on a protecting layer and a portion of an opposite surface near the trailing side end thereof and a thin film element. It is thus possible to avoid direct contact between the thin film element and the disk surface, and thus prevent damage to the thin film element and wearing thereof even if a slider and the disk surface repeatedly slide on each other.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a magnetic head mounted on, forexample, a hard disk drive, and comprising a slider, and particularly toa magnetic head wherein the starting force required for starting arecording medium is decreased, and at the same time, a thin film elementprovided on the trailing side end of a slider can be protected fromcontact with the recording medium, and a production method thereof.

[0003] 2. Description of the Related Art

[0004]FIG. 8A is a plan view showing a magnetic head mounted on a harddisk with a surface opposite to a recording medium upward, FIG. 8B is asectional view of the magnetic head shown in FIG. 8A taken along lineIB-IB of FIG. 8A, and FIG. 8C is a sectional view of the magnetic headshown in FIG. 8A taken along line IC-IC of FIG. 8A.

[0005] In the magnetic head H shown in these drawings, the upstream side(a) in the movement direction X of a disk is referred to as the leadingside, and the downstream side (b) is referred to as the trailing side. Aslider 1 comprises a ceramic material, and rails 4 are formed on bothsides of an air groove 7 in a portion of the slider 7 opposite to thedisk. As shown in FIG. 8B, each of the rails 4 has a convex sectionalshape, and an opposite surface (air bearing surface; ABS) 5 is formed atthe top of the convex sectional shape of each of the rails 4 so as tocontact the recording surface of the disk when the magnetic head H isstopped. Each of the opposite surfaces 5 is processed to a crown shapewith a predetermined curvature. As shown in FIG. 8C, each of the rails 4has an inclined surface 6 formed at the leading-side end thereof.

[0006] As shown in FIGS. 8A and 8C, at the end 2 of the slider 1 on thetrailing side (b) thereof are provided a thin film element 3 and aprotecting film 8 for covering the thin film element 3. The thin filmelement 3 comprises a MR head (reading head) for detecting a fringingmagnetic field to read a magnetic signal, and an inductive head (writinghead) having a coil patterned thereon. The protecting film 8 comprises anon-magnetic ceramic material, e.g., aluminum oxide (Al₂O₃) or the like.

[0007] The slider 1 of the magnetic head H is supported by a flexurefixed at the tip of a load beam comprising a leaf spring so as to beurged on the disk by the elastic force of the load beam. The magnetichead H is used for a so-called CSS (Contact Start Stop) system hard diskdevice in which when the disk is stopped, the opposite surfaces 5 of theslider 1 contact the recording surface of the disk due to the elasticforce. When the disk is started, a flow of air is guided into betweenthe slider 1 and the surface of the disk along the movement direction (Xdirection) of the disk, and the opposite surfaces 5 are subjected tofloating force of the flow of air to float the slider 1 at a shortdistance from the surface of the disk.

[0008] In the floating state, the slider 1 is in an inclined statewherein the leading side (a) rises from the disk more than the trailingside (b). In this floating state, the MR head of the thin film element 3detects a magnetic signal from the disk, or the inductive head writesthe magnetic signal.

[0009] A disk driving motor provided on the CSS system hard disk devicerequires starting torque sufficient to securely start the disk and theslider sliding. When the starting torque required for starting the diskand the slider is increased, a large motor must be used for the harddisk drive, thereby limiting miniaturization of the device and causingthe problem of increasing power consumption.

[0010] The torque required for starting the disk depends upon the staticfrictional force between the opposite surfaces 5 of the slider 1 and thedisk surface. In order to decrease the starting torque required forstarting the disk, it is necessary to decrease the static frictionalforce.

[0011] In a conventional hard disk serving as a recording medium, sincethe disk surface has relatively high roughness, even if the oppositesurfaces 5 of the slider are relative smooth surfaces, it is possible todecrease the real contact area between the disk surface and the oppositesurfaces 5, and consequently possible to decease the static frictionalforce.

[0012] However, a recent hard disk for high-density recording has hadthe tendency that the disk surface becomes smooth. The reason for thisis that when the surface of the hard disk is roughed, protrusions arenonuniformly formed on the disk surface, and thus the slider 1 in afloating state collides with the protrusions on the disk surface todamage the disk surface during magnetic recording or reproduction by themagnetic head. When the slider 1 repeatedly collides with and contactsthe protrusions on the disk surface, the thin film element 3 mounted atthe end 2 of the slider 1 is damaged, thereby deteriorating recordingand reproduction performance. In addition, heat is generated bycollision and contact between the slider 1 and the disk surface, therebycausing the problem of generating noise in the reproduced output.Particularly, in a hard disk for high-density recording, it is necessaryto decrease the spacing between the thin film element 3 and the disksurface, and thus avoid the formation of irregular protrusions on thedisk surface. Therefore, the hard disk for high-density recording tendto have a smooth disk surface close to a mirror surface.

[0013] When the disk surface of the hard disk is a smooth surface, theabove problems can be solved. However, when both the disk surface andthe opposite surfaces 5 of the slider are smooth surfaces, a lubricantor water film coated on the disk surface are present between the diskand the slider 1 when the hard disk device is stopped, and thus theslider 1 is adhered to the disk. Therefore, the static frictional forceis increased when the disk is started, and large starting torque is thusrequired for starting the disk.

[0014] Therefore, in a hard disk device having a smooth disk surface forhigh-density recording, it is necessary to rough the opposite surfaces 5of the slider 1 to decrease the real contact area between the oppositesurfaces 5 and the disk surface.

[0015] As a method for roughing the opposite surfaces 5 of the slider 1,for example, a texturing method is known in which the opposite surfaces5 are chemically etched or sputtered to form protrusions on the oppositesurfaces 5.

[0016] However, this method easily damages the thin film element 3 bychemical etching and increases an element recess. An increase in theelement recess causes an increase in spacing loss between the thin filmelement 3 and the disk surface, and deterioration in the efficiency ofsignal writing and reading sensitivity. In some cases, the thin filmelement 3 is broken, thereby making normal reading and writingimpossible.

[0017] The above texturing process is difficult to form protrusionsaround the thin film element 3 without damaging the thin film element 3.Therefore, no protrusion is formed around the thin film element 3, andthus the thin film element 3 contact directly the disk surface when thehard disk is stopped. When sliding of the hard disk is started, the thinfilm element 3 is liable to be damaged and worn.

[0018] Further, the texturing process requires complicated steps andmany steps, and the processing equipment used in the texturing processis very expensive.

SUMMARY OF THE INVENTION

[0019] The present invention has been achieved for solving the aboveproblems of a conventional magnetic head, and an object of the presentinvention is to provide a magnetic head which permits easy formation ofprotrusions on opposite surfaces of a slider using a laser, andparticularly a magnetic head which permits formation of protrusionsaround a thin film element without damage to the thin film element, anda production method thereof.

[0020] In order to achieve the object, the present invention provides amagnetic head comprising a slider which contacts the surface of arecording medium when the recording medium is stopped, and which assumesa floating state after the recording medium is started wherein thetrailing side end thereof floats or slides on the recording medium dueto the floating force of a flow of air on the surface of the recordingmedium; a magnetic recording and/or reproducing thin film elementprovided at the trailing side end of the slider; and a protecting filmfor covering the thin film element; wherein protrusions are formed onthe surface of the protecting layer opposite to the recording mediumand/or a portion of the surface of the slider opposite to the recordingmedium in the vicinity of the trailing side end.

[0021] Also protrusions are preferably formed on a portion of theopposite surface other than the vicinity of the trailing side end.

[0022] Further, the protrusions formed in the vicinity of the trailingside end are preferably denser than the protrusions formed on a portionof the opposite surface other than the vicinity of the trailing sideend.

[0023] Further, the protrusions formed on the protecting layer and theopposite surface preferably have an average height of 5 to 50 nm.

[0024] On the protecting layer and the opposite surface is preferablyformed a hard carbon thin film which is more preferably deposited to athickness of 5 to 15 nm.

[0025] In the present invention, the slider can be formed by usingAl₂O₃—TiC comprising a mixture of Al₂O₃ (aluminum oxide) crystal grainsand TiC (titanium carbide) crystal grains, or Si (silicon).

[0026] The present invention also provides a method of producing amagnetic head comprising a slider which is made of a ceramic material,which contacts the surface of a recording medium when the recordingmedium is stopped, and which assumes a floating state after therecording medium is started wherein the trailing side end thereof floatsor slides on the recording medium due to the floating force of a flow ofair on the surface of the recording medium; a magnetic recording and/orreproducing thin film element provided at the trailing side end of theslider; and a protecting film for covering the thin film element; themethod comprising smoothing the surface of the protecting layer oppositeto the recording medium and the surface of the slider opposite to therecording medium, and then applying a laser beam to at least theprotecting layer and/or the trailing side end of the opposite surface toform protrusions.

[0027] After the protrusions are formed, a hard carbon thin film ispreferably formed on the protecting layer and the opposite surface.

[0028] Since the hard carbon thin film is formed on the protecting layerand the opposite surface, the protrusions formed on the protecting layerand the opposite surface are hardly worn even if the slider and the disksurface repeatedly slide on each other.

[0029] In the present invention, a Nd-YAG laser can be used as a laserfor emitting the laser beam, and a secondary higher harmonic orquaternary higher harmonic can be used as the laser beam of the Nd-YAGlaser.

[0030] As the laser for emitting the laser beam, an excimer layer canalso be used.

[0031] In the present invention, the protrusions are formed on at leastthe protecting layer around the thin film element and/or a portion ofthe opposite surface of the slider in the vicinity of the trailing sideend thereof so that the thin film element does not contact directly thedisk surface. Therefore, even if the slider and the disk surfacerepeatedly slide on each other, the thin film element is protected bythe protrusions, thereby hardly causing the problem of breaking the thinfilm element.

[0032] Also, in the present invention, the laser beam is applied to theopposite surface of the slider and the protecting layer, which arepolished, to form the protrusions. The use of the laser facilitates theformation of the protrusions, and facilitates the formation of theprotrusions in any desired region. It is thus possible to easily formthe protrusions around the thin film element without damaging the thinfilm element. In addition, since neither mechanical stress nor thermalstress is applied to the opposite surface of the slider and theperiphery of the thin film element during laser processing, neithercrack nor strain in a junction occurs. It is also possible toarbitrarily change the shape of the protrusions and the average heightthereof by appropriately selecting the type of the laser used and theoutput of the laser beam.

[0033] Although, when the slider is in a floating state, the trailingside end thereof with the thin film element provided floats or slides onthe recording medium, but the sliding may be either continuous orincontinuous.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034]FIG. 1A is a plan view showing a magnetic head in accordance witha first embodiment of the present invention with a surface opposite to adisk upward, FIG. 1B is a sectional view taken along line IB-IB in FIG.1A, and FIG. 1C is a sectional view taken along line IC-IC in FIG. 1A;

[0035]FIGS. 2A to 2D are plan views each showing the shape and positionof the protrusions formed in the periphery of a thin film element of themagnetic head shown in FIG. 1;

[0036]FIG. 3 is an enlarged front view showing the shape of a protrusionformed by using a Nd-YAG laser and quaternary higher harmonic as thelaser beam of the laser, FIG. 3A being an enlarge front view when theoutput of the laser beam was 1.5 mW, and FIG. 3B being an enlarged frontview when the output of the laser was 2 mW or 3 mW;

[0037]FIG. 4A is a plan view showing a magnetic head in accordance witha second embodiment of the present invention with a surface opposite toa disk upward, and FIG. 4B is a right side view of the magnetic headshown in FIG. 4A;

[0038]FIG. 5 is a graph showing the relation between the starting torqueand the number of CSS of a magnetic head having the shape shown in FIG.1 and a plurality of protrusions (average height; 30 nm, diameter; 4 μm)formed on an opposite surface of a slider;

[0039]FIG. 6 is a graph showing the relation between the starting torqueand the average height of protrusions after 30000 cycles of CSS, whichwere measured for a plurality of magnetic heads having the shape shownin FIG. 1 and different average heights of protrusions (diameter; 5 μm,protrusion interval; 30 μm) formed in an opposite surface of a slider;

[0040]FIG. 7 is a graph showing the relation between PW50 and thespacing in a magnetic head having the shape shown in FIG. 1 and aplurality of protrusions (average height; 30 μm, diameter; 4 μm) formedin an opposite surface of a slider; and

[0041]FIG. 8A is a plan view showing a conventional magnetic head with asurface opposite to a disk upward, FIG. 8B is a sectional view takenalong line IB-IB in FIG. 8A, and FIG. 8C is a sectional view taken alongline IC-IC in FIG. 8A.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0042]FIG. 1A is a plan view showing a magnetic head mounted on a harddisk or the like in accordance with a first embodiment of the presentinvention, with a surface opposite to a recording medium upward, FIG. 1Bis a sectional view of the magnetic head shown in FIG. 1A taken alongline IB-IB in FIG. 1A, and FIG. 1C is a sectional view of the magnetichead shown in FIG. 1A taken along line IC-IC in FIG. 1A.

[0043] The slider 1 of the magnetic head H shown in FIG. 1 comprises aceramic material and has an air groove 7 formed in a portion thereofopposite to the hard disk serving as a recording medium, and rails 4formed on both sides of the air groove 7.

[0044] In the present invention, as the ceramic material for forming theslider 1, aluminum oxide-titanium carbide Al₂O₃—TiC comprising a mixtureof Al₂O₃ (aluminum oxide) crystal grains and TiC (titanium carbide)crystal grains, or Si (silicon) can be used.

[0045] Al₂O₃—TiC has excellent wear resistance and cutting performance,and silicon is suitable for fine processing.

[0046] Besides the above two ceramic materials, Al₂O₃, Al₂O₃—TiO₃,CeO₂—ZrO₂, Y₂O₃—ZrO₂, TiC, SiC, WC, Si₃N₄ and AlN can also be used, andthese ceramic materials have excellent wear resistance and heatresistance.

[0047] In the present invention, the ceramic materials may be usedsingly or as a compound comprising at least two materials.

[0048] Each of the rails 4 has a convex sectional shape, as shown inFIG. 1B, in which an opposite surface (air bearing surface; ABS) 5 isformed at the top of each of rails 4. Each of the opposite surfaces 5 isformed in a crown shape having a predetermined curvature, manyprotrusions being formed on the surface by a laser.

[0049] On the end surface (end) 2 of the slider 1 on the trailing side(b) thereof is provided a thin film element 3 which is covered with aprotecting layer 8 comprising a ceramic material such as aluminum oxide(Al₂O₃) except the surface opposite to the recording medium, as shown inFIGS. 1A and 1C. Like the opposite surfaces 5, many protrusions are alsoformed on the protecting layer 8 by a laser.

[0050] The thin film element 3 comprises a laminate of a magneticmaterial such as permalloy (Ni—Fe alloy), and an insulation materialsuch as aluminum oxide, and includes a magnetic sensing region forreproducing the magnetic recorded signals recorded on the disk or amagnetic recording region for recording magnetic signals on the disk, orboth the magnetic sensing region and the magnetic recording region. Themagnetic recording region comprises a MR head composed of amagnetoresistive element (MR element). The magnetic sensing regioncomprises an inductive head having a coil and core which are patternedthereon.

[0051] The slider 1 of the magnetic head H shown in FIG. 1 is supportedby a flexor provided at the tip of a load beam. The slider is urged on ahard disk serving as a recording medium by predetermined force.

[0052] The magnetic head is used for a CSS system hard disk device(magnetic recording/reproducing device). When the disk is stopped, theopposite surfaces 5 of the slider 1 contact the disk surface. When thedisk is moved in the X direction shown in FIG. 1, the whole slider 1floats on the disk surface by a flow of air introduced into between theslider 1 and the disk to create a floating state wherein the leadingside (a) more rises from the disk than the trailing side (b).Alternatively, only the leading side (b) floats on the disk surface tocreate a floating state wherein the end on the trailing side (b) slideson the disk surface in continuous or non continuous contact therewith.

[0053] In the present invention, many protrusions are formed on theopposite surfaces 5 of the slider and the protecting layer 8 by a laser,as described above. Although the type of the laser used will bedescribed later, laser formation of the protrusions is very simple, andis capable of reducing the number of the steps and substantiallyprecisely forming the protrusions at any desired positions. It is thuspossible to form the protrusions on the protecting layer 8 near the thinfilm element 3 without damaging the thin film element 3. During laserprocessing, neither mechanical stress nor thermal stress is applied tothe slider 1, and thus neither crack nor strain in a junction occurs.

[0054] Of the protrusions formed on the opposite surfaces 5 and theprotecting layer 8 by the laser, the shape and position of theprotrusions formed around the thin film element 3 will be describedbelow with reference to FIG. 2. The protrusions formed on a portionother than the vicinity of the thin film element 3 have the same shapeas those of the protrusions shown in FIG. 2.

[0055]FIG. 2 is an enlarged plan view showing the protrusions formed inthe region 11 shown in FIG. 1.

[0056] In FIG. 2A, protrusions 10 are formed near the trailing side end2 of each of the opposite surfaces 5. The protrusions 10 have the shapeshown in FIG. 3A or 3B. In FIG. 2B, the protrusions 10 are also formedon the protecting layer 8. In FIG. 2C, the protrusions 10 are formednear the trailing side end 2 of each of the opposite surfaces 5, andboth sides of the thin film element 3. In the present invention, thenumber of the protrusions 10 and the position thereof are not limited.However, as many protrusions as possible are preferably formed near thethin film element 3 (on the protecting layer 8 and near the trailingside end 2 of each of the opposite surfaces 5).

[0057] When the protrusions 10 are formed on the leading side of thethin film element 3, for example, in the vicinity of the trailing sideend 2 of each of the opposite surfaces 5, as shown in FIG. 2A, it ispossible to prevent dust (contamination) on the disk from contacting thethin film element 3, and thus eliminate the possibility that thefunction of the thin film element 3 deteriorates. When the protrusions10 are formed on both sides of the thin film element 3, as shown in FIG.2C, it is possible to prevent contact of dust or the like on the diskduring movement of the magnetic head between tracks, and thus eliminatethe possibility that the function of the thin film element 3deteriorates.

[0058] In the present invention, the shape of the protrusions 10 is notlimited to those shown in FIGS. 2A to 2C, and protrusions 11 may beformed in a wall-like shape, as shown in FIG. 2D. In this way, theprotrusions can be formed around the thin film element 3 by using alaser without damaging the thin film element 3, and protrusions havingany desired shape can easily be formed.

[0059] The protrusions formed on the opposite surfaces 5 and theprotecting layer 8 preferably have an average height within the range of5 to 50 nm. If the average height of the protrusions is less than 5 nm,the real contact area between each of the opposite surfaces 5 of theslider 1 and the disk surface is increased, thereby increasing startingtorque. If the average height of the protrusions exceeds 50 nm, thespacing is increased, and thus the recording density cannot beincreased. Although described below, it was confirmed that the use ofthe laser used in the present invention enables the formation of theprotrusions having an average height within the range of 5 to 50 nm.

[0060] The protrusions formed on the protecting layer 8 and a portion ofeach of the opposite surfaces 5 in the vicinity (in the periphery of thethin film element 3) of the trailing side end 2 are preferably denserthan the protrusions formed on a portion of each of the oppositesurfaces 5 other than the vicinity of the trailing side end 2.

[0061] The protrusions formed on the protecting layer and a portion ofeach of the opposite surfaces 5 in the vicinity of the trailing side end2 frequently contacts and slides on the disk, and are thus easily worn.Therefore, when the protrusions are densely formed on the protectinglayer 8 and a portion of each of the opposite surfaces 5 in the vicinityof the trailing side end 2, it is possible to decrease the surfacepressure applied to each of the protrusions and suppress the occurrenceof wearing. However, if the protrusions are also densely formed on aportion of each of the opposite surfaces 5 other than the vicinity ofthe trailing side end 2, the starting torque in CSS is increased.Therefore, if the protrusions are densely formed only on the protectinglayer 8 and regions of the opposite surfaces 5 in the vicinity of theend 2 on the trailing side (b), it is possible to decrease the startingtorque in CSS and produce a magnetic head having excellent wearresistance.

[0062] In the present invention, since the protrusions are formed aroundthe thin film element 3 and over the entire opposite surfaces 5, it ispossible to prevent adhesion by a lubricant or water film coated on thedisk surface. It is thus possible to decrease the starting torque forstarting the disk. Particularly, by forming the protrusions around thethin film element 3, direct contact of the thin film element 3 with thedisk surface can be avoided. Thus if the slider and the disk surfacerepeatedly slide on each other, the thin film element 3 is neitherdamaged nor worn.

[0063] The opposite surfaces 5 and the protecting layer 8 are preferablycoated with a hard carbon film so that even if the protrusions formed onthe opposite surfaces 5 and the protecting layer 8 contact the disksurface, the protrusions are hardly worn. The hard carbon thin filmpreferably has a thickness of about 5 to 15 nm.

[0064] The laser used in the present invention will be described indetail below.

[0065] The laser device used in the present invention can be exemplifiedby a Nd-YAG laser which exhibits excellent mass productivity and whichis capable of easily forming the protrusions with appropriatedimensions. As the laser beam of the Nd-YAG laser, a quaternary higherharmonic (266 nm) or a secondary higher harmonic is preferably used. Thequaternary higher harmonic and secondary higher harmonic have a shortwavelength, and high-precision processing can be expected by using thequaternary or secondary higher harmonic as the laser beam.

[0066] Besides the Nd-YAG laser, an excimer laser (wavelength; 120 to400 nm) using a gas such as Ar, Kr, Xe, ArF, KrF or the like may beused. The excimer laser has high energy and is capable of properlyforming the protrusions even on a ceramic material having a singlecomposition.

[0067] In order to form the protrusions by using the laser, thepredetermined positions on the opposite surfaces 5 of the slider and theprotecting layer 8 may be irradiated with the laser beam of the laser.The positions irradiated with the laser beam rise to form theprotrusions. Before irradiation with the laser beam, the oppositesurfaces 5 and the protecting layer 8 are preferably polished so thatthe average roughness (Ra) on the central line is 3 nm or less.

[0068] After the protrusions have been formed on the opposite surfaces 5of the slider 1 and the protecting layer 8, the hard carbon thin filmhaving a thickness 5 to 15 nm is preferably formed to cover the oppositesurfaces 5 and the protecting layer 8.

[0069] The protrusions were actually formed by the Nd-YAG laser orexcimer laser, and the shape and dimensions of the protrusions weremeasured.

[0070] (Experiment 1: Processing by Nb-YAG Laser)

[0071] The slider 1 was formed of aluminum oxide-titanium carbide, andthe opposite surfaces 5 of the slider 1 were polished so that theroughness (Ra) on the central line was 3 nm or less.

[0072] The opposite surfaces 5 were irradiated with laser by using thequaternary higher harmonic of the Nd-YAG laser while changing the outputto 1.5 mW, 2 mW and 3 mW to form protrusions with each output.

[0073] The protrusions were measured by a surface shape measuringapparatus using laser interference. As a result, with an output of 1.5mW, the protrusions had the shape shown in FIG. 3A, and with an outputof 2 mW or 3 mW, the protrusions had the shape shown in FIG. 3B. Alsothe height h, width w and depth d of each of the protrusions weremeasured. The results are shown in Table 1. TABLE 1 YAG4 Laser 3 mW (1.5μJ/pulse) 2 mW (1.0 μJ/pulse) 1.5 mW (0.75 μJ/pulse) MeasurementMeasurement Measurement point H (nm) D (nm) W (μm) point H (nm) D (nm) W(μm) point H (nm) D (nm) W (μm)  1 48.8 117 7.8  1 29.7 11.3 4.2  1 26.84.2  2 28.3 124.7 8.3  2 48.8 46 4  2 25.4 3.9  3 24.7 110.5 7.5  3 48.939.5 3.2  3 28.1 2.6  4 35.4 143.6 8.6  4 46.4 35 3.9  4 24.5 4.4  561.3 233.3 8.5  5 24.7 37.5 4.8  5 29.7 4.2  6 46.1 111.2 8.3  6 29.441.1 3.9  6 30 4.7  7 24.3 148.1 8.6  7 32 26.8 2.7  7 20.8 3.9  8 61.8173.4 7.8  8 24.7 64 5.3  8 26.4 4.2  9 42 142.7 8.6  9 23.2 54.4 5.6  922 3.6 10 38.8 135.6 8.7 10 26.5 42.6 4.4 10 18.8 2.5 Average 41.15144.01 8.27 Average 33.43 39.83 4.2 Average 25.25 3.82 Range 37.5 122.81.2 Range 25.7 52.7 2.9 Range 11.2 2.2 max 61.8 233.3 8.7 max 48.9 645.6 max 30 4.7 min 24.3 110.5 7.5 min 23.2 11.3 2.7 min 18.8 2.5

[0074] The table indicates that with an output of 1.5 mW, 2 mW and 3 mW,the average height of the protrusions was about 25 nm, 33 nm and 41 nm,respectively. It was thus found that the shape of the protrusions can bechanged by changing the output, and that the average height can beincreased by increasing the output.

[0075] As a result of EPMA (Electron Probe MIcroanalysis) of theprotrusions and the peripheries thereof, the protrusions contained alarge amount of Ti, and the peripheries thereof contained a large amountof Al. This indicates that in the case of aluminum oxide-titaniumcarbide, the protrusions are mainly formed of TiC. Since TiC has higherhardness than Al₂O₃, the protrusions made of TiC exhibits improved wearresistance and longer life, as compared with protrusions made of Al₂O₃.Even when the protecting layer 8 is formed, the wear resistance of theprotrusions made of TiC is more improved than the protrusions made ofAl₂O₃.

[0076] (Experiment 2: Processing by Excimer Laser)

[0077] A plurality of protrusions were formed on the opposite surfaces 5of the slider 1 comprising aluminum oxide-titanium carbide by using anexcimer laser (wavelength: 248 nm) using KrF gas.

[0078] As a result of measurement by a surface shape measuring apparatususing laser interference, the average height was 16 nm, the maximumheight was 25 nm and the minimum height was 11 nm.

[0079] As a result of EPMA of the protrusions and the peripheriesthereof, the protrusions contained a large amount of Ti, and theperipheries thereof contained a large amount of Al. It was thus foundthat in the case of aluminum oxide-titanium carbide, the protrusions aremainly made of TiC. This experiment was same as Experiment 1 in thepoint that the protrusions are preferably made of TiC.

[0080] It was thus found that the use of the Nb-YAG laser or excimerlaser permits the formation of the protrusions having an average heightin the range of 5 to 50 nm, and that the shape and average height of theprotrusions can be arbitrarily changed by changing the output of thelaser beam of the Nb-YAG layer.

[0081] Description will now be made of a second method of forming theprotrusions by using the laser.

[0082] On the opposite surfaces 5 of the slider 1, which were polished,was coated a thermosetting resin. Since the thickness of thethermosetting resin is equal to the thickness of the protrusions, thethickness of the thermosetting resin is preferably about 5 to 50 nm.

[0083] Predetermined positions of the opposite surfaces were irradiatedwith the laser beam of the laser to cure the irradiated thermosettingresin. The uncured thermosetting resin was removed by etching.Photoresist may be used in place of the thermosetting resin.

[0084] This method is capable of easily forming the protrusions at anydesired positions.

[0085]FIG. 4A is a plan view of a magnetic head H in accordance with asecond embodiment of the present invention with a surface opposite to arecording medium upward. FIG. 4B is a right side view of the magnetichead shown in FIG. 4A.

[0086] As shown in the drawings, the opposite surface 5 of the slider 1is continued on the leading side (a), not divided into two surfaces,unlike the opposite surfaces 5 shown in FIG. 1.

[0087] Like the magnetic head H shown in FIG. 1, the magnetic head Hshown in FIG. 4 has protrusions which are formed on the opposite surface5 and the periphery of the thin film element 3 by a laser. Therefore, itis possible to avoid direct contact between the thin film element 3 andthe disk surface, decrease the static frictional force between theopposite surface 5 and the disk surface, and decrease the startingtorque required for starting the disk.

[0088] Since the floating state of the magnetic head H shown in FIG. 4is more stable than the magnetic head shown in FIG. 1, the spacing canbe decreased, and the magnetic head H can be more effectively applied tohigh-density recording.

EXAMPLE

[0089] The magnetic head provided with the slider will be describedbelow with reference to examples.

[0090] A plurality of protrusions 10 having an average height of 30 nmand a diameter of 4 μm were formed on the opposite surfaces 5 of theslider 1, and a hard carbon thin film of about 10 nm was formed to coverthe opposite surfaces 5 to produce a magnetic head having the shapeshown in FIG. 1. The thus-produced magnetic head was set in a hard diskdevice which was then started by a CSS (contact•start•stop) system, andthe starting torque was measured.

[0091]FIG. 5 is a graph showing the relation between the number of CSScycles and the starting torque. In FIG. 5, a dotted line is drawn at astarting torque of 25 (g·f), which indicate rating torque. In caseswherein starting torque higher than this line is required, a troubleeasily occurs in which the hard disk device is not operated.

[0092] As shown in FIG. 5, the starting torque is substantially constantat about 4 (g·f) even if the number of CSS cycles increases. The reasonfor a staring torque of as low as about 4 (g·f) is that the real contactarea between the slider 1 and the disk surface is decreased by formingthe protrusions on the opposite surfaces. The reason why a substantiallyconstant starting torque can be maintained even when the number of CSScycles is increased is that the coating of the opposite surfaces 5 withthe hard carbon thin film prevents wearing even if the protrusionsformed on the opposite surfaces 5 repeatedly slide on the disk surface.

[0093] Next, magnetic heads having the shape shown in FIG. 1 anddifferent average heights of protrusions were produced in which theprotrusions had a diameter of 5 μm and were formed on the oppositesurfaces 5 of the slider 1 using a laser at constant intervals of 30 μm.Each of the thus-produced magnetic heads was set in a hard disk device,and the necessary starting torque was measured after the hard diskdevice had been started 30000 times.

[0094]FIG. 6 is a graph showing the relation between the average heightof the protrusions and the starting torque.

[0095]FIG. 6 indicates that as the average height of the protrusionsincreases, the starting torque decreases. It was confirmed from theexperimental results that the starting torque can be decreased bysetting the average height of the protrusions to 5 nm or more.

[0096] This is possibly due to the fact that the real contact areabetween the opposite surfaces 5 and the disk surface can be decreased byincreasing the average height of the protrusions, and the staticfrictional force is consequently decreased.

[0097] Next a magnetic head having the shape shown in FIG. 1 wasproduced by forming a plurality of protrusions 10 having an averageheight of 30 nm ad a diameter of 4 m on the opposite surfaces 5 of theslider using a laser, and then forming a hard carbon thin film of about10 nm to coat the opposite surfaces 5. In this case, the element recesswas 5 nm. Like the opposite surfaces 5, a hard carbon thin film of 10 nmwas also formed on the disk surface to cover it.

[0098] The thus-produced magnetic head was set in a hard disk device,and the width dimensions of pulse signals were measured with differentspacings.

[0099]FIG. 7 is a graph showing the relation between the spacing andPW50. “PW50” represents the width dimension of a pulse signal at a ½height.

[0100]FIG. 7 indicates that as the spacing increases, PW50 increases.Namely, as the spacing increases, the width dimension of a pulse signalincreases, and thus the recording density decreases. Therefore thespacing is preferably as small as possible. Particularly, in order toobtain recording signals of 1 G (giga) per square inch, PW50 ispreferably 0.38 μm or less, i.e., the spacing is preferably 75 nm orless.

[0101] Since the average height of the protrusions formed on theopposite surfaces 5 is obtained by subtracting the thickness (in thisexperiment, 10 nm) of the hard carbon thin film formed on each of theopposite surfaces 5 and the disk surface and the element recess (in thisexperiment, 5 nm) from the spacing, the preferably average height of theprotrusions is found to be 50 nm or less.

[0102] Even in the floating state wherein only the leading side (a) ofthe slider 1 floats on the disk surface and continuously orincontinuously slides on the trailing surface, in the present invention,a constant spacing is always kept between the slider 1 and the disksurface by the height of the protrusions and the thickness of the hardcarbon thin film, and the output of the magnetic head can thus bestabilized.

[0103]FIGS. 6 and 7 indicate that the average height of the protrusionsformed on the opposite surfaces 5 and the protecting layer 8 ispreferably within the range of 5 to 50 nm, as described above.

[0104] In accordance with the present invention, it is possible to formprotrusions in the periphery of a thin film element by a Nd-YAG layer orexcimer laser without damaging the thin film element. Therefore the thinfilm element does not contact directly the disk surface, and thus thethin film element is neither damaged nor worn.

[0105] Also the use of the laser permits the formation of theprotrusions by a small number of steps, and the formation of theprotrusions in any desired portions. Further, since neither mechanicalstress nor thermal stress is applied to the slider during laserprocessing, neither crack nor strain in a junction occurs. Further, theshape and the average height of the protrusions can be appropriatelyadjusted by changing the type and output of the laser beam of the laserused.

What is claimed is:
 1. A magnetic head comprising: a slider whichcontacts the surface of a recording medium when the recording medium isstopped, and which assumes a floating state where the trailing side endthereof floats or slides on the recording medium by the floating forceof a flow of air on the surface of the recording medium after therecording medium has been started; a magnetic recording and/orreproducing thin film element provided at the trailing side end of theslider; and a protecting layer provided to cover the thin film element;wherein protrusions are formed on the surface of the protecting layeropposite to the recording medium and/or a portion of the surface of theslider opposite to the recording medium in the vicinity of the trailingside end.
 2. A magnetic head according to claim 1, wherein theprotrusions are also formed on a portion of the opposite surface otherthan the vicinity of the trailing side end.
 3. A magnetic head accordingto claim 1, wherein the protrusions formed on the protecting layer andthe opposite surface have an average height of 5 to 50 nm.
 4. A magnetichead according to claim 1, wherein the slider is formed of Al₂O₃—TiC(aluminum oxide.titanium carbide) comprising a mixture of Al₂O₃(aluminum oxide) crystal grains and TiC (titanium carbide) crystalgrains.
 5. A magnetic head according to claim 1, wherein the slider isformed of Si (silicon).
 6. A magnetic head according to claim 2, whereinthe protrusions formed in the vicinity of the trailing side end aredenser than the protrusions formed on a portion of the opposite surfaceother than the vicinity of the trailing side end.
 7. A magnetic headaccording to claim 2, wherein a hard carbon thin film is formed on theprotecting layer and the opposite surface.
 8. A magnetic head accordingto claim 2, wherein the slider is formed of Al₂O₃—TiC (aluminumoxide.titanium carbide) comprising a mixture of Al₂O₃ (aluminum oxide)crystal grains and TiC (titanium carbide) crystal grains.
 9. A magnetichead according to claim 2, wherein the slider is formed of Si (silicon).10. A magnetic head according to claim 4, wherein a hard carbon thinfilm is formed on the protecting layer and the opposite surface.
 11. Amagnetic head according to claim 4, wherein the slider is formed ofAl₂O₃—TiC (aluminum oxide.titanium carbide) comprising a mixture ofAl₂O₃ (aluminum oxide) crystal grains and TiC (titanium carbide) crystalgrains.
 12. A magnetic head according to claim 4, wherein the slider isformed of Si (silicon).
 13. A magnetic head according to claim 3,wherein the protrusions formed on the protecting layer and the oppositesurface have an average height of 5 to 50nm.
 14. A magnetic headaccording to claim 3, wherein a hard carbon thin film is formed on theprotecting layer and the opposite surface.
 15. A magnetic head accordingto claim 3, wherein the slider is formed of Al₂O₃—TiC (aluminumoxide.titanium carbide) comprising a mixture of Al₂O₃ (aluminum oxide)crystal grains and TiC (titanium carbide) crystal grains.
 16. A magnetichead according to claim 3, wherein the slider is formed of Si (silicon).17. A magnetic head according to claim 7, wherein the thickness of thehard carbon thin film is 5 to 15 nm.
 18. A magnetic head according toclaim 7, wherein the slider is formed of Al₂O₃—TiC (aluminumoxide.titanium carbide) comprising a mixture of Al₂O₃ (aluminum oxide)crystal grains and TiC (titanium carbide) crystal grains.
 19. A magnetichead according to claim 7, wherein the slider is formed of Si (silicon).20. A magnetic head according to claim 10, wherein the slider is formedof Al₂O₃—TiC (aluminum oxide.titanium carbide) comprising a mixture ofAl₂O₃ (aluminum oxide) crystal grains and TiC (titanium carbide) crystalgrains.
 21. A magnetic head according to claim 10, wherein the slider isformed of Si (silicon).
 22. A magnetic head according to claim 13,wherein a hard carbon thin film is formed on the protecting layer andthe opposite surface.
 23. A magnetic head according to claim 13, whereinthe slider is formed of Al₂O₃—TiC (aluminum oxide.titanium carbide)comprising a mixture of Al₂O₃ (aluminum oxide) crystal grains and TiC(titanium carbide) crystal grains.
 24. A magnetic head according toclaim 13, wherein the slider is formed of Si (silicon).
 25. A magnetichead according to claim 14, wherein the thickness of the hard carbonthin film is 5 to 15 nm.
 26. A magnetic head according to claim 14,wherein the slider is formed of Al₂O₃—TiC (aluminum oxide.titaniumcarbide) comprising a mixture of Al₂O₃ (aluminum oxide) crystal grainsand TiC (titanium carbide) crystal grains.
 27. A magnetic head accordingto claim 14, wherein the slider is formed of Si (silicon).
 28. Amagnetic head according to claim 17, wherein the slider is formed ofAl₂O₃—TiC (aluminum oxide.titanium carbide) comprising a mixture ofAl₂O₃ (aluminum oxide) crystal grains and TiC (titanium carbide) crystalgrains.
 29. A magnetic head according to claim 17, wherein the slider isformed of Si (silicon).
 30. A magnetic head according to claim 22,wherein the thickness of the hard carbon thin film is 5 to 15 nm.
 31. Amagnetic head according to claim 22, wherein the slider is formed ofAl₂O₃—TiC (aluminum oxide.titanium carbide) comprising a mixture ofAl₂O₃ (aluminum oxide) crystal grains and TiC (titanium carbide) crystalgrains. 32 A magnetic head according to claim 22, wherein the slider isformed of Si (silicon).
 33. A magnetic head according to claim 25,wherein the slider is formed of Al₂O₃—TiC (aluminum oxide.titaniumcarbide) comprising a mixture of Al₂O₃ (aluminum oxide) crystal grainsand TiC (titanium carbide) crystal grains. 34 A magnetic head accordingto claim 25, wherein the slider is formed of Si (silicon).
 35. Amagnetic head according to claim 30, wherein the slider is formed ofAl₂O₃—TiC (aluminum oxide.titanium carbide) comprising a mixture ofAl₂O₃ (aluminum oxide) crystal grains and TiC (titanium carbide) crystalgrains.
 36. A magnetic head according to claim 30, wherein the slider isformed of Si (silicon).
 37. A method of producing a magnetic headcomprising a slider which is made of a ceramic material, which contactsthe surface of a recording medium when the recording medium is stopped,and which assumes a floating state where the trailing side end thereoffloats or slides on the recording medium by the floating force of a flowof air on the surface of the recording medium after the recording mediumhas been started, a magnetic recording and/or reproducing thin filmelement provided at the trailing side end of the slider, and aprotecting layer provided to cover the thin film element, wherein themethod comprising: smoothing the protecting layer opposite to therecording medium and the surface of the slider opposite to the recordingmedium; and applying a laser beam to at least the protecting layerand/or the trailing side end of the opposite surface to form protrusionsthereon.
 38. A method of producing a magnetic head according to claim37, further comprising forming a hard carbon thin film on the protectinglayer and the opposite surface to cover them after the protrusions areformed.
 39. A method of producing a magnetic head according to claim 37,wherein a Nd-TAG layer is used as a laser for emitting the laser beam,and a secondary or quaternary harmonic is used as the laser beam of theNd-TAG laser.
 40. A method of producing a magnetic head according toclaim 37, wherein an excimer laser is used as a laser for emitting thelaser beam.
 41. A method of producing a magnetic head according to claim38, wherein a Nd-TAG layer is used as a laser for emitting the laserbeam, and a secondary or quaternary harmonic is used as the laser beamof the Nd-TAG laser.
 42. A method of producing a magnetic head accordingto claim 38, wherein an excimer laser is used as a laser for emittingthe laser beam.